Revert "External Version bump for alpinelinux new version string "3.18""

This reverts commit d74f1db1cd427d9263a5d147a91b2ca56e65daa7.

roles/netbootxyz/defaults/main.yml

@@ -131,8 +131,8 @@ releases:
     mirror: http://dl-cdn.alpinelinux.org
     name: Alpine Linux
     versions:
-    - code_name: v3.18
-      name: '3.18'
+    - code_name: v3.17
+      name: '3.17'
     - code_name: edge
       name: Edge (development)
   anarchy: